A good novelisation of a strong TV story, let down somewhat by the limited page length, causing the book to rush at times.
I like the general build up, and the 'hiding' as such of the main enemy, similar to Earthshock in that regard, though the cover does spoil the enemy, but the characters don't find out until quite late in the piece, which adds a nice layer of mystery to it.
This one very much feels like a deliberate forerunner of the Third Doctor's UNIT years, with the (now) Brigadier Lethbridge-Stewart returning, the first time UNIT and Benton feature in a story, and a very Earth centric tale.
The Doctor, Jamie and Zoe all get some good moments in here, Jamie showing his normal action man type of stuff, and Zoe showing her cleverness quite well in a couple of memorable scenes, and the Doctor being his trademark self, scruff, comical at times but clever and determined as well.
The UNIT crew also good in here, as well as the other one off characters, though we only see the Brigadier and Benton again.
The antagonists are good here as well, well fleshed out, and quite menacing at times, and showing that certainly not stupid either. Builds to a strong finish, and just a shame it couldn't be a longer novel.